180th meridian

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Line across the Earth
180th meridian
The International Date Line zigzags around the 180th Meridian.

The 180th meridian or antimeridian is the meridian which is 180° east or west of the Prime Meridian with which it forms a great circle. It is common to both east longitude and west longitude. It is used as the basis for the International Date Line because it for the most part passes through the open waters of the Pacific Ocean. However, the meridian passes through Russia and Fiji as well as Antarctica.

Starting at the North Pole and heading south to the South Pole, the 180th meridian passes through:

Co-ordinates
(approximate)
Country, territory or sea Notes
Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found. Arctic Ocean
Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found.  Russia Chukotka Autonomous OkrugWrangel Island
Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found. Chukchi Sea
Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found.  Russia Chukotka Autonomous Okrug
Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found. Bering Sea
Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found. Amchitka Pass Passing just east of Semisopochnoi Island, Alaska,  United States (at Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found.)
Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found. Pacific Ocean Passing just east of Nukulaelae atoll,  Tuvalu (at Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found.)
Passing just west of the island of Cikobia,  Fiji (at Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found.)
Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found.  Fiji Islands of Vanua Levu, Rabi, and Taveuni
Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found. Pacific Ocean Passing just east of the island of Moala,  Fiji (at Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found.)
Passing just west of the island of Totoya,  Fiji (at Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found.)
Passing just east of the island of Matuku,  Fiji (at Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found.)
Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found. Southern Ocean
Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found. Antarctica Ross Dependency, claimed by  New Zealand
180° Meridian, Taveuni, Fiji

The meridian also passes between (but not particularly close to):

The only place where roads cross this meridian, and where there are buildings very close to it, is in Fiji.

Software representation problems

Many geographic software libraries or data formats project the world to a rectangle; very often this rectangle is split exactly at the 180th meridian. This often makes it impossible to do simple tasks (like representing an area, or a line) over the 180th meridian. Some examples:

  • The GeoJSON specification doesn't mention handling of the 180th meridian in its specification, as such, representations of lines crossing the 180th meridian can just as well be interpreted as going around the world.
  • In OpenStreetMap, areas (like the boundary of Russia) are split at the 180th meridian.

See also